Put shy characters out to discover a disease (6)
I believe the answer is:
typhus
'disease' is the definition.
(typhus is a kind of disease)
'put shy characters' is the wordplay.
'characters' indicates anagramming the letters.
'put'+'shy'='putshy'
'putshy' anagrammed gives 'TYPHUS'.
'out to discover a' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for typhus that I've seen before include "Disease found in spy hut, strangely" , "Infectious disease with fever and purple rash" , "Dangerous fever transmitted by lice" , "Infectious disease often spread by lice" , "Disease causing high fever and skin rash" .)